Technical Field
The present invention relates to organic electrical element using compound for organic electrical element, and electronic device thereof.
Background Art
In general, an organic light emitting phenomenon refers to a phenomenon in which electric energy is converted into light energy of an organic material. An organic electric element utilizing the organic light emitting phenomenon usually has a structure including an anode, a cathode, and an organic material layer interposed therebetween. In many cases, the organic material layer may have a multilayered structure including multiple layers made of different materials in order to improve the efficiency and stability of an organic electric element, and for example, may include a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, or the like.
A material used as an organic material layer in an organic electric element may be classified into a light emitting material and a charge transport material, for example, a hole injection material, a hole transport material, an electron transport material, an electron injection material, and the like according to its function.
Currently, the power consumption is required more and more as size of display becomes larger and larger in the portable display market. Therefore, the power consumption is a very important factor in the portable display with a limited power source of the battery, and efficiency and life span issue also must be solved.
Efficiency, life span, driving voltage, and the like are correlated with each other. For example, if efficiency is increased, then driving voltage is relatively lowered, and the crystallization of an organic material due to Joule heating generated during operation is reduced as driving voltage is lowered, as a result of which life span shows a tendency to increase. However, efficiency cannot be maximized only by simply improving the organic material layer. This is because long life span and high efficiency can be simultaneously achieved when an optimal combination of energy levels and T1 values, inherent material properties (mobility, interfacial properties, etc.), and the like among the respective layers included in the organic material layer is given.
Further, in order to solve the emission problem with a hole transport layer in a recent organic electric element, an emission-auxiliary layer is formed between the hole transport layer and a light emitting layer, and it is time to develop different material of emission-auxiliary layers according to respective pixel-domain (R, G, B) of light emitting layers.
In general, an exciton is formed by recombination of an electron which transfers from an electron transport layer to a light emitting layer and a hole which transfers from a hole transport layer to the light emitting layer.
However, it mainly has a low T1 value because a material used in a hole transporting layer should have a low HOMO value, thereby excitons generated from a light emitting layer are transported to the hole transporting layer, resulting in a charge unbalance in the light emitting layer. Thus, light emission occurs in the hole transporting layer or at an interface of the hole transporting layer so that color purity, efficiency and lifespan of the organic electroluminescent device are reduced.
Further, when a material with rapid hole mobility is used in order to reduce a driving voltage in the organic electroluminescent device, it shows tendency to lower the efficiency. The general organic electric element has a hole mobility higher than an electron mobility. This causes a charge unbalance in the light emitting layer resulting in low emitting efficiency and lifespan.
Therefore, in order to solve a problem of a hole transport layer, it needs to form the light emitting layer as material which has a hole transport ability to have a proper driving voltage, high T1 (electron block) value and wide bandgap.
These requirements are not satisfied only by structural characteristics of a core of the emission-auxiliary layer material, and it is possible to satisfy these requirements when characteristics of core and sub substituents have an appropriate combination. Therefore, it is necessary strongly to develop of the material for the emission-auxiliary layer having high T1 energy value and wide band gap, to improve efficiency and lifespan of the organic electric element.
In order to allow an organic electric element to fully exhibit the above-mentioned excellent features, it should be prerequisite to support a material forming an organic material layer of the element, for example, a hole injection material, a hole transport material, a light emitting material, an electron transport material, an electron injection material, an emission-auxiliary layer material or the like, by a stable and efficient material. However, such a stable and efficient organic material layer material for an organic electric element has not yet been fully developed. Accordingly, there is a continuous need to develop new materials for an organic material layer, specially, there are strong needs to develop materials for an emission-auxiliary layer and a hole transport layer.